526 LARID^E. 



In the autumn moult the black portions of the plumage 

 become white on the head, neck and under parts, and slate- 

 grey on the mantle ; a specimen in the Editor's collection, 

 obtained near Valencia, in Spain, on the 25th of July, pre- 

 sents a remarkably piebald appearance. Some black is never 

 absent from the nape and ear-coverts, and in mature and 

 vigorous birds the black of the under parts soon begins to 

 make its reappearance. The immature bird in August has 

 the bill livid brown, lores and forehead white, crown and nape 

 brownish-grey, a dark streak behind the ear-coverts ; sides of 

 the neck white, tinted with buff ; upper back and scapulars 

 slate-grey, tipped or overlaid with brown, which gradually 

 wears off; back grey, mottled with brown, rump white, pass- 

 ing to grey on the tail-coverts ; tail-feathers grey, darker and 

 browner at tips ; primaries darker on inner webs than in the 

 adults ; under wing-coverts and under parts white. By the 

 end of the following summer the brown tips have completely 

 passed away, leaving only a mottled bar along the carpals to 

 indicate immaturity ; and in the following spring, when the 

 bird is nearly two years old, it assumes the black nuptial 

 garb. The tail-feathers, however, do not become quite white 

 for some years, and it may be that this takes longer with the 

 females than with the males ; otherwise there appear to be 

 no appreciable external differences between the sexes when 

 fully matured. The nestling is of a nearly uniform rufous- 

 buff, slightly darker on the throat ; the crown and back streaked 

 and mottled with blackish-brown. 



The young of this species may be distinguished from that 

 of H. nigra by its longer feet, with much more deeply incised 

 webs ; paler rump and tail, the latter being also less 

 pointedly forked ; the distinct white interior of the inner 

 webs of the outerprimaries, and the pure white not grey 

 of the under wing-coverts. But the young of the White- 

 winged Black Tern are not always to be so easily distinguished 

 from small Asiatic examples of the Whiskered Tern, H. 

 hybrida, which will next be considered, although in European 

 examples of each species the superior dimensions of the latter 

 are a sufficient indication. 



